关键词: 钻杆, S135 钢级, 高韧性, 冲击功, 钻杆螺纹

Abstract: Petroleum drilling has seen more and more deep wells, super-deep wells and horizontal wells with large displacement in recent years. The wear and inefficiency rates of drilling tools are increased owing to significant improvement of drilling rate and drilling pressure. The API-certified drilling rod of S135 steel grade has high risks for such well cases and application. The reliability of highly-reliable drilling rod of S grade is improved at the three positions of the drilling rod that are the easiest to become inefficient. The thermal treatment process parameters are optimized to solve the contradictions in improvement of strength and tenacity so far as some of drilling rod materials is concerned. Impact energy of the developed tube body at -20℃ is raised by more than 109 percent under the high strength of 930. 825MPa, while horizontal impact energy of joint at - 10℃ is raised by more than 48 percent. The unique tube - end homogeneously heating technology, matched with mechanical tube-end thickening process, is used to the tube end making the length of inner transitional zone exceed 130mm. R≥300mm at the vanishing point of inner transitional zone, effectively reducing stress concentration to avoid drill rod thorn leakage. A new type of joint thread (BHDX) is adopted for the joint, thus improving torsional strength more than 35 percent as compared to API joint of the same specification. The designed service life of the drilling rod is significantly increased as compared to the ordinary API -certified drilling rod of S steel grade, obviously improving application reliability of the drilling rod.